Electrostatic chuck with porous plug

ABSTRACT

Electrostatic chucks and method for forming the same are described herein. The electrostatic chucks include a backside gas passage having a ceramic porous plug secured therein by a ceramic body of the chuck with a ceramic-to-ceramic body. In one example, ceramic porous plug is sintered with the ceramic body.

BACKGROUND

Field

Implementations described herein generally relate to a substrate supportassembly and more particularly to a substrate support assembly having abonded porous plug and methods of bonding the porous plug with thesubstrate support assembly.

Description of the Related Art

Substrate support assemblies are widely used to support substrateswithin semiconductor processing systems during processing. Oneparticular type of substrate support assembly includes a ceramicelectrostatic chuck mounted on a cooling base. Electrostatic chucksgenerally retain the substrate in a stationary position duringprocessing. Electrostatic chucks contain one or more embedded electrodeswithin a ceramic body. As an electrical potential is applied between theelectrodes and a substrate disposed on the ceramic body, anelectrostatic attraction is generated, which holds the substrate againsta support surface of the ceramic body. The force generated may have acapacitive effect due to a potential difference between the substrateand the electrodes or, in the case of ceramic bodies comprised ofsemiconducting materials having a relatively low resistivity, whichallow charge migration within the ceramic body to the surfaceapproximate the substrate, a Johnsen-Rahbeck effect. Electrostaticchucks utilizing capacitive and Johnsen-Rahbeck attractive forces arecommercially available from a number of sources.

To control the substrate temperature during processing, a backside gasis provided through a gas passage formed in the ceramic body to thesupport surface of the ceramic body below the substrate. The backsidegas fills the interstitial area between the ceramic body and thesubstrate, thus providing a heat transfer medium that enhances the rateof heat transfer between the substrate and the substrate support. Aporous ceramic plug is positioned in the gas passage to prevent ignitionof the backside gas flowing through the gas passage within the ceramicbody. The porous plug is secured to the ceramic body using an adhesive.

However, insertion of the plug into the ceramic body is unpredictable.The variation in the quality of plug insertion allows erosion of theadhesive retaining the plug to the ceramic body over the service life ofthe electrostatic chuck, and facilitates premature arcing failures andsecondary particle contamination of the substrate. Variation isexasperated by manual application of the adhesive used to secure theplug. Further, the bond adhesion may further weaken due to plasma, CTEmismatch and friction between the ceramic body, porous plug and/orsubstrate when exposed to elevated temperatures. Once the adhesive iscompromised, contamination of the substrate is inevitable as materialeroded from the adhesive layer becomes a process contaminant thatproduces defects and reduces product yields. Additionally, thecompromised porous plug to ceramic body bond further allows attack ofthe bond layer securing the electrostatic chuck to the cooling base byprocess and other gases, dramatically reducing the service life of theelectrostatic chuck.

Therefore, there is a need for an improved electrostatic chuck andmethods of manufacturing the same.

SUMMARY

Electrostatic chucks and method for forming the same are describedherein. The electrostatic chucks include a ceramic body having abackside gas passage in which a ceramic porous plug is secured using aceramic-to-ceramic bond. In one example, ceramic porous plug is sinteredwith the ceramic body. Although sintering a ceramic porous plug togetherwith a ceramic body is described as forming an electrostatic chuck as aprimary example, the method described herein can also be practiced tojoin a ceramic porous plug and a ceramic structure other than anelectrostatic chuck to form a single fired ceramic body with anintegrally sintered porous plug disposed within a passage of the ceramicstructure.

In another example, an electrostatic chuck includes a ceramic body and aceramic porous plug disposed in a gas passage of the ceramic body. Theceramic body includes a substrate support surface and a bottom surface.The ceramic body includes an electrode and a gas passage extendingbetween the substrate support surface and the bottom surface. Theceramic porous plug is secured in the gas passage by aceramic-to-ceramic bond.

In another example, an electrostatic chuck is provided that is suitablefor use in a semiconductor processing chamber. The electrostatic chuckincludes a ceramic body and a ceramic porous plug. The ceramic body hasa substrate support surface and a bottom surface, an electrode and a gaspassage extending between the substrate support surface and the bottomsurface. The ceramic porous plug is disposed in the gas passage and issintered to the ceramic body. A temperature control base is secured tothe bottom surface of the ceramic body by an adhesive layer. Thetemperature control base includes a gas delivery hole that is alignedwith the gas passage formed in the ceramic body. The aligned gasdelivery hole and gas passage are configured to flow backside gas to asupport surface of the ceramic body.

In still another example, a method for fabricating an electrostaticchuck is provided. The method includes disposing a ceramic porous plugat least partially in a hole formed in a ceramic structure, the holeconfigured to become a fluid passage; and sintering the ceramicstructure and ceramic porous plug to form a ceramic-to-ceramic bondtherebetween.

In one example, the ceramic structure is a ceramic body of anelectrostatic chuck. In other examples, the ceramic structure may be aplate, a shield, a liner, a body, a filter, a container or gasdistribution plate, among others structures.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentdisclosure can be understood in detail, a more particular description ofthe implementations, briefly summarized above, may be had by referenceto implementations, some of which are illustrated in the appendeddrawings. It is to be noted, however, that the appended drawingsillustrate only typical implementations of this disclosure and aretherefore not to be considered limiting of its scope, for the disclosuremay admit to other equally effective implementations.

FIG. 1 is a schematic view of a processing chamber including a substratesupport assembly having a co-sintered porous plug according to one ormore implementations of the present disclosure.

FIG. 2 is a schematic cross-sectional view of the substrate supportassembly having a porous plug co-sintered with a ceramic body of anelectrostatic chuck according to one or more implementations of thepresent disclosure.

FIG. 3 is a partial cross-sectional exploded view of the electrostaticchuck of FIG. 2 according to one or more implementations of the presentdisclosure.

FIG. 4 is a cross-sectional view of a portion of the electrostatic chucksintered with a porous plug according to one or more implementations ofthe present disclosure.

FIG. 5 is a cross-sectional view of a portion of the electrostatic chucksintered with a porous plug according to one or more implementations ofthe present disclosure.

FIG. 6 is a cross-sectional view of a portion of a substrate supportassembly illustrating an electrostatic chuck sintered with a porousplug, the porous plug mating with a temperature control base of thesubstrate support assembly according to one or more implementations ofthe present disclosure

FIG. 7 is a flowchart of a method of forming an electrostatic chuckhaving a co-sintered porous plug according to one or moreimplementations of the present disclosure.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is contemplated that elements and features of oneimplementation may be beneficially incorporated in other implementationswithout further recitation.

Many of the details, scale, dimensions, angles and other features shownin the Figures are merely illustrative of particular implementations.Accordingly, other implementations can have other details, components,dimensions, angles and features without departing from the spirit orscope of the present disclosure. In addition, further implementations ofthe disclosure can be practiced without several of the details describedbelow.

DETAILED DESCRIPTION

The following disclosure describes electrostatic chucks having a ceramicbody in which a ceramic porous plug is secured by a ceramic-to-ceramicbond. Methods for forming the same are also described. Theceramic-to-ceramic bond between the ceramic body and the ceramic porousplug eliminates the use of bonding materials to secure the ceramicporous plug in a backside gas passage of the ceramic body. Consequently,contamination of substrate processed on the electrostatic chuck andchuck failure modes are reduced, while chuck service life is extended.Thus, ceramic-to-ceramic bonding of the ceramic porous plug to theceramic body results in a robust and reliable electrostatic chuck withvastly improved chuck-to-chuck performance uniformity. These benefitsprovide a significant reduction in the cost of ownership, whilesynergistically improving production yields and production capacity dueto reduced particle contamination and longer mean times between serviceintervals associated with the use of the electrostatic chuck.

Turning now to FIG. 1 , a schematic diagram of a processing chamber 100including a substrate support assembly 110 is illustrated according toone or more implementations of the present disclosure. The substratesupport assembly 110 includes an electrostatic chuck 112 disposed on atemperature control base 114. The electrostatic chuck 112 has a ceramicporous plug secured in a backside gas passage using a ceramic-to-ceramicbond as later described below that provides the advantages describedabove. As additionally noted herein, the ceramic porous plug mayalternatively be secured in a fluid passage of other types of ceramicstructures using a ceramic-to-ceramic bond.

The processing chamber 100 includes a chamber body 102, which defines aprocessing volume 104. The substrate support assembly 110 is positionedwithin the processing volume 104. The chamber body 102 includes aceiling 106, a bottom wall 107, and one or more chamber walls 108. Theceiling 106 can be composed of a dielectric material.

The substrate support assembly 110 is generally supported above thebottom wall 107 of the processing chamber 100 by a shaft 116 coupled tothe temperature control base 114. The substrate support assembly 110 isfastened to the shaft 116 such that the substrate support assembly 110can be removed from the shaft 116, refurbished, and re-fastened to theshaft 116. The shaft 116 is sealed to the temperature control base 114to isolate various conduits and electrical leads disposed therein fromthe process environment within the processing chamber 100.Alternatively, the electrostatic chuck 112 and the temperature controlbase 114 maybe disposed on an insulating plate that is attached to aground plate or chassis. Further, the ground plate may be attached toone or more of the ceiling 106, the bottom wall 107, and the one or morechamber walls 108.

The electrostatic chuck 112 is generally circular in form but canalternatively comprise other geometries to accommodate non-circularsubstrates. For example, the electrostatic chuck 112 may comprise asquare or rectangular substrate when used in processing display glass,such as such as glass for flat panels displays. The electrostatic chuck112 includes a substrate support surface 120 for supporting a substrate,for example, a substrate 122, for example, a semiconductor substrate.The temperature of the substrate 122 is controlled by controlling thetemperature of the electrostatic chuck 112. The temperature control base114 includes heating and/or cooling elements that are utilized to heatand/or cool the electrostatic chuck 112 that is secured to the topsurface of the temperature control base 114. In one example, thetemperature control base 114 may include resistive heaters and/orconduits for flowing a heat transfer fluid such that heat may betransfer to, or pulled away from, the electrostatic chuck 112 thuscontrolling the temperature of the electrostatic chuck 112 along withthe substrate 122 positioned thereon. To promote heat transfer betweenthe electrostatic chuck 112 and the substrate 122, a backside gas (e.g.,helium, nitrogen, argon or other gas) may be provided by a gas source124 to the interstitial space defined between the substrate 122 and thesubstrate support surface 120 of the electrostatic chuck 112. Thebackside gas provides a heat transfer medium that facilitates heattransfer between the substrate 122 and the substrate support assembly110, thus enhancing control the temperature of the substrate 122 duringprocessing, cleaning or when otherwise desired.

The electrostatic chuck 112 may also include one or more heaters. Forexample, the heaters may be resistive heaters or the like. Theelectrostatic chuck 112 include one or more electrodes, which may becoupled to a power supply 125. At least one of the electrodes of theelectrostatic chuck 112 is utilized to generate the electrostatic forcethat secures the substrate 122 to the substrate support surface 120 ofthe electrostatic chuck 112. Optional other electrodes disposed withinthe electrostatic chuck 112 may be utilized for plasma control,cleaning, or other purpose.

The processing chamber 100 further includes at least an inductive coilantenna segment 130A and a conductive coil antenna segment 130B, bothpositioned exterior to the ceiling 106. The inductive coil antennasegment 130A and the conductive coil antenna segment 130B are eachcoupled to a radio-frequency (RF) source 132 that produces an RF signal.The RF source 132 is coupled to the inductive coil antenna segment 130Aand to the conductive coil antenna segment 130B through a matchingnetwork 134. The substrate support assembly 110 is also coupled to an RFsource 136 that produces an RF signal. The RF source 136 is coupled tothe substrate support assembly 110 through a matching network 138. Theone or more chamber walls 108 can be conductive and connected to anelectrical ground 140.

The pressure within the processing volume 104 of the processing chamber100 is controlled using a throttle valve 142 situated between theprocessing chamber 100 and a vacuum pump 144. The temperature at thesurface of the one or more chamber walls 108 is controlled usingliquid-containing conduits (not shown) that are located in the one ormore chamber walls 108 of the processing chamber 100.

A system controller 150 is coupled to the various components of theprocessing chamber 100 to facilitate control of the substrate processingprocess. The system controller 150 includes memory 152, a centralprocessing unit (CPU) 154, and support circuits (or I/O) 156. Softwareinstructions and data can be coded and stored within the memory forinstructing the CPU. The system controller 150 can communicate with oneor more of the components of the processing chamber 100 via, forexample, a system bus. A program (or computer instructions) readable bythe system controller 150 determines which tasks are performable on asubstrate. In some aspects, the program is software readable by thesystem controller 150. Although a single system controller 150 is shown,it should be appreciated that multiple system controllers can be usedwith the aspects described herein.

In one example of operation, the substrate 122 is placed on thesubstrate support surface 120 of the substrate support assembly 110.Backside gas is provided between the substrate 122 and the substratesupport surface 120 of the electrostatic chuck 112 to enhancetemperature control of the substrate 122 during processing. Gaseouscomponents are supplied from a gas panel 160 to the processing chamber100 through entry ports 162 to form a gaseous mixture in the processingvolume 104 of the processing chamber 100. The gaseous mixture in theprocessing volume 104 is ignited into a plasma in the processing chamber100 by applying RF power from the RF sources 132, 136 respectively tothe inductive coil antenna segment 130A, the conductive coil antennasegment 130B and to the substrate support assembly 110. Additionally,chemically reactive ions are released from the plasma and strike thesubstrate 122; thereby removing exposed material from the substrate'ssurface.

Although the exemplary processing chamber 100 detailed above isillustrated as an inductively coupled etch processing chamber, theprocessing chamber 100 may also be configured as another type of etchprocessing chamber, a chemical vapor deposition chamber, a physicalvapor deposition chamber, an ion implantation chamber or othersemiconductor, flat panel, or similar processing chamber where the useof a ceramic-to-ceramic bond of a porous plug in a ceramic body isdesired.

FIG. 2 is a partial cross-sectional view of the substrate supportassembly 110 having a ceramic porous plug 202 secured to a ceramic body204 of the electrostatic chuck 112 without the use of adhesives. Theceramic body 204 of the electrostatic chuck 112 is fabricated from aceramic material, such as alumina, aluminum nitride or other suitableceramic material. For example, the ceramic body 204 of the electrostaticchuck 112 may be fabricated from a low resistivity ceramic material, forexample, a material having a resistivity between about 1×E⁹ to about1×E¹¹ ohm-cm. Examples of low resistivity materials include ceramicssuch as alumina doped with titanium oxide or chromium oxide, dopedaluminum oxide, doped boron-nitride and the like. Other materials ofcomparable resistivity, for example, aluminum nitride, may also be used.Such ceramic materials having relatively low resistivity generallypromote a Johnsen-Rahbek attractive force between the substrate andelectrostatic chuck 112 when power is applied to a chucking electrode218 embedded within the ceramic body 204. Alternatively, the ceramicbody 204 may comprise ceramic materials having a resistivity equal to orgreater than 1×E¹¹ ohms-cm may also be used. Further, the ceramic body204 of the electrostatic chuck 112 may be fabricated from an aluminumoxide. The aluminum oxide can have high resistivity and be used inCoulombic mode.

The ceramic body 204 is formed from green sheets or layers that aresintered together to form a solid contiguous body of ceramic. In theexample depicted in FIG. 2 , dashed lines illustrate 3 layers 212, 214,216 that are stacked together prior to sintering. The number of layersare simply for illustration, as ceramic body 204 may be formed from anynumber of desired layers. The chucking electrode 218 (and otherelectrodes and heater, which present) is disposed between the layers,for example layers 214, 216, prior to sintering such that aftersintering, the chucking electrode 218 is embedded in the solid mass ofceramic comprising the ceramic body 204.

The chucking electrode 218 is fabricated from an electrically conductivematerial such as copper, graphite, tungsten, molybdenum and the like.Various implementations of electrode structures include, but are notlimited to, a pair of coplanar D-shaped electrodes, coplanarinterdigital electrodes, a plurality of coaxial annular electrodes, asingular, circular electrode or other structure. The chucking electrode218 is coupled to the power supply 125 by a feed-through 220 disposed inthe substrate support assembly 110. The power supply 125 may drive theelectrode 218 with a positive or negative voltage. For example, thepower supply 125 may drive the electrode 218 with a voltage of about−1000 volts or a voltage of about 2500 volts. Alternatively, othernegative voltages or other positive voltages may be utilized.

In some examples, each of the layers 212, 214, 216 may be composed ofthe same type of ceramic material. For example, all of the layers 212,214, 216 may be formed from ceramic powder having the same powder size,which generally results in uniform grain size across the layers 212,214, 216 after sintering. In another example, one or more of the layers212, 214, 216 may be composed of a different type of ceramic material.For example, the top layer 216 may be formed from a ceramic powderhaving one size powder, while the bottom layer 212 may be formed from aceramic powder having a different size powder, which generally resultsin a different grain size in different regions (i.e., formed from thelayers 212, 214, 216) after sintering.

The ceramic body 204 also includes a plurality of backside gas passages206. The backside gas passages 206 are open to the substrate supportsurface 120 of the electrostatic chuck 112 so that a backside gas may beprovided between the substrate and electrostatic chuck to enhance heattransfer as discussed above. The one or more of the backside gaspassages 206 forming each backside gas channel through the electrostaticchuck 112 include a hole 208 formed in a bottom surface 238 of theceramic body 204. The hole 208 is sized to receive at least a portion ofthe ceramic porous plug 202 such that a backside gas delivery channel isformed through the passages 206, plug 202 and hole 208 to enablebackside gas to be provide to the substrate support surface 120 in aregion below the substrate to enhance heat transfer between theelectrostatic chuck 112 and substrate. The transition between thepassages 206 and the hole 208 forms a step 210 upon which the theceramic porous plug 202 may abut to reliably position the plug 202within the hole 208. Although the hole 208 and cross section of theceramic plug 202 are typically circular, any complimentary geometry maybe utilized. For example, the ceramic plug 202 may have a square profilethat fits within a square shaped mating geometry of the hole 208.Moreover, although only one backside gas delivery channel is illustratedin FIG. 2 , it is contemplated that a plurality of similarly constructedbackside gas delivery channels are distributed across the substratesupport surface 120 of the electrostatic chuck 112.

The ceramic porous plug 202 is secured in the hole 208 by aceramic-to-ceramic bond. That is, the outer diameter surface of theceramic porous plug 202 is directly bonded using a sintering process tothe inside diameter of the hole 208 formed in the ceramic body 204without the use of adhesives. For example, the ceramic-to-ceramic bondcreated by the sintering process fuses the ceramic material of theceramic porous plug 202 together with the ceramic material of theceramic body 204 to form a singular solid mass by using a combination ofpressure and heat without melting the material of the plug 202 and body204.

The porous plug 202 is fabricated from a ceramic material, such asalumina, aluminum nitride or other suitable ceramic material. Theceramic porous plug 202 may be fabricated from the same types ofmaterials used to fabricate the ceramic body 204. The ceramic porousplug 202 may be entirely formed from ceramic powder having the samepowder size, which generally results in uniform grain size across theplug 202. In some examples, the ceramic porous plug 202 may be formed byusing different types of ceramic material in different regions of theplug 202. For example, the ceramic porous plug 202 may include an upperregion 222 that is adjacent the step 210 of the hole 208 and a lowerregion 224 that is adjacent the bottom surface 238 of the ceramic body204. The powder size may be different in each of the regions 222, 224,resulting in a different grain size of the ceramic material in each ofthe regions 222, 224. The powder size in each of the regions 222, 224may be the same or different from the powder size utilized in one ormore of the layers 212, 214, 216 forming the ceramic body 204. Thisresults in the grain size in one or both regions 222, 224 of the plug202 being different than grain size in one or more of the layers 212,214, 216 of the ceramic body 204. In one example, the grain size in oneor both regions 222, 224 of the plug 202 is larger than grain size of atleast one or more or all of the layers 212, 214, 216 of the ceramic body204.

The hole 208 formed in the ceramic body 204 aligns with a gas deliveryhole 230 formed through the temperature control base 114. The gasdelivery hole 230 is coupled to gas source 124 that provides thebackside gas, such as helium, nitrogen, argon or other suitable gas.

The adhesive layer 226 joining the electrostatic chuck 112 to thetemperature control base 114 includes a gap 228 that allows the backsidegas to flow from the gas delivery hole 230 formed in the base 114 to thepassages 206 formed in the chuck 112. The adhesive layer 226 may be anacrylic or silicon-based adhesive, epoxy, neoprene based adhesive, anoptically clear adhesive such as a clear acrylic adhesive, or othersuitable adhesive materials.

The temperature control base 114 is generally fabricated from a metallicmaterial such as stainless steel, aluminum, aluminum alloys, among othersuitable materials. Further, the temperature control base 114 includesone or more heat transfer elements 232, such as resistive heaters,thermoelectric devices, or conduits for flowing heat transfer fluid,among others. In the example depicted in FIG. 2 , the heat transferelements 232 are in the form of channels for flowing heat transfer fluidprovided from a heat transfer fluid source 236. The heat transfer fluidsource 236 is coupled to the channels (e.g., heat transfer elements 232)by a conduit 234.

To further the description of the ceramic porous plug 202, the porousplug 202 can have an open-pore structure meaning that pores in theporous structure are interconnected allowing fluids to flow through theporous plug 202. In some implementations, more than half of the cells inthe open-pore structure are interconnected. For example, the porous plug202 provides a path for pressurized gas to flow to the substrate supportsurface 120 of the electrostatic chuck 112 from the gas delivery hole230 formed through the temperature control base 114. The passagewaysand/or pores that allow gas flow through the ceramic porous plug 202 aresized to reduce the probability that plasma will ignite in the adhesivegap 228 defined between the electrostatic chuck 112 and the temperaturecontrol base 114 as compared to a design not including the porous plug202. In one example, ceramic porous plug 202 may have a porosity ofabout 30 to about 80 percent. Alternatively, the porous plug may have aporosity of less than 30 percent or greater than 80 percent.

The porous plug 202 can have any suitable shape. In someimplementations, the porous plug 202 has a cylindrical shape. Othersuitable shapes include T-shaped, taper shaped, and rectangular shaped,among other shapes.

As discussed above, the ceramic-to-ceramic bond between the porous plug202 and the ceramic body 204 allows the plug 202 to be secured ceramicbody 204 without in the adhesives. Advantageously, the plug 202 whenco-sintered with the ceramic body 204 forms a singular structure that ishighly resistive to erosion from the process gases, has significantlylonger service life, and is much less likely to shed particles thatcould become a process contaminant and lower production yields ascompared to conventional electrostatic chucks that utilize adhesive tosecure porous plugs.

FIG. 3 is a partial cross-sectional exploded view of a portion of theelectrostatic chuck 112 of FIG. 2 , according to one or moreimplementations of the present disclosure. In the exploded view of FIG.3 , the ceramic porous plug 202 is illustrated prior to insertion intothe hole 208 formed in the bottom surface 238 of the ceramic body 204 ofthe electrostatic chuck 112. In one example, the ceramic porous plug 202may be fully formed and sintered to form a solid body of ceramic. Afterinsertion, the ceramic porous plug 202 and the ceramic body 204 aresintered together to form a solid body of ceramic.

In another example, the ceramic porous plug 202 may be partiallysintered prior to insertion into the hole 208 of the ceramic body 204 ofthe electrostatic chuck 112. After insertion, the ceramic porous plug202 and the ceramic body 204 are sintered together to form a solid bodyof ceramic.

In still another example, the ceramic porous plug 202 may be in a fullygreen state prior to insertion into the hole 208 of the ceramic body 204of the electrostatic chuck 112. After insertion, the ceramic porous plug202 and the ceramic body 204 are sintered together to form a solid bodyof ceramic.

As shown in FIG. 3 , the ceramic porous plug 202 includes a top surface302, a bottom surface 306 and a sidewall 304. The sidewall 304 may bethe outside diameter of the ceramic porous plug 202. In implementationswhere the sectional profile of the ceramic porous plug 202 is not round,the sidewall 304 or sidewalls 304 simply define the outercircumferential surface of the plug 202, connecting the top and bottomsurfaces 302, 306 of the plug 202, that mates against and is sinteredtogether with the sidewalls of the complimentarily shaped hole 208formed in the ceramic body 204.

FIG. 4 is a cross-sectional view of a portion of the electrostatic chuck112 sintered with a ceramic porous plug 202 according to one or moreimplementations of the present disclosure. In the example depicted inFIG. 4 , the bottom surface 306 of the ceramic porous plug 202 issubstantially flush with the bottom surface 238 of the ceramic body 204.The bottom surface 306 of the ceramic porous plug 202 may be made flushwith the bottom surface 238 of the ceramic body 204 by any suitabletechnique. In one example, the bottom surface 306 of the ceramic porousplug 202 is ground co-planar with the bottom surface 238 of the ceramicbody 204.

FIG. 5 is cross-sectional view of a portion of the ceramic body 204 withco-sintered the ceramic porous plug 202 according to anotherimplementation of the present disclosure. In the example depicted inFIG. 5 , the bottom surface 306 of the ceramic porous plug 202 isrecessed from the bottom surface 238 of the ceramic body 204. The bottomsurface 306 of the ceramic porous plug 202 may be recessed from thebottom surface 238 of the ceramic body 204 by any suitable technique. Inone example, the bottom surface 306 of the ceramic porous plug 202 ismachined below the bottom surface 238 of the ceramic body 204. Inanother example, a height of the ceramic porous plug 202 is smaller thana depth of the hole 208 formed in the ceramic body 204.

FIG. 6 is a cross-sectional view of a portion of a substrate supportassembly 110 illustrating an electrostatic chuck 112 sintered with aceramic porous plug 202, according to another implementation of thepresent disclosure. In FIG. 6 , the ceramic porous plug 202 protrudesfrom the bottom surface 238 of the ceramic body 204. For example, theceramic porous plug 202 may have a height that is greater than a depthof the hole 208 formed in the ceramic body 204.

In the example depicted in FIG. 6 , the bottom surface 306 of theceramic porous plug 202 protrudes from the bottom surface 238 of theceramic body 204 a sufficient distance to shield the adhesive layer 226.In this manner, the adhesive layer 226 is shielded (i.e., substantiallyprevented) from being exposed to process or other gases that may betraveling though the porous plug 202. In one example, the bottom surface306 of the ceramic porous plug 202 protrudes a distance the bottomsurface 238 of the ceramic body 204 such that the bottom surface 306 isessentially coplanar with or extends below the top surface 240 of thetemperature control base 114.

In the example depicted in FIG. 6 , the bottom surface 306 of theceramic porous plug 202 extends into a recess 602 in the top surface 240of the temperature control base 114. The gas delivery hole 230terminates at the recess 602 such that backside gas can readily flowthrough the gas delivery hole 230, through the plug 202 and into thebackside gas passages 206. As the ceramic porous plug 202 extendsthrough the gap 228 formed in the adhesive layer 226 and into the recess602, the ceramic porous plug 202 effectively shields the adhesive layer226 from gases flowing between the gas delivery hole 230 and thebackside gas passages 206.

FIG. 7 is a flowchart of a method 700 of forming a ceramic structuresintered with porous plug 202 according to one or more implementationsof the present disclosure. Although the method 700 describes sintering aceramic porous plug 202 together with a ceramic structure to form asingle fired ceramic body, the method 700 is particularly advantageousto form an electrostatic chuck 112. The method 700 can be practiced tojoin a ceramic porous plug 202 and a ceramic structure other than anelectrostatic chuck to form a single fired ceramic body with an integralporous plug with a passage within the ceramic structure. Somenon-limiting examples of ceramic structure include a plate, a shield, aliner, a body, a filter, a container and gas distribution plate, amongothers.

The method 700 begins at operation 702 by disposing a ceramic porousplug 202 at least partially in a hole 208 formed in a ceramic structure.In one example, the hole 208 is configured to become a fluid passage ofthe fired ceramic structure.

In an particular implementation of the method 700 utilized to form anelectrostatic chuck 112, operation 702 includes disposing a ceramicporous plug 202 at least partially in a hole 208 formed in a green sheetof ceramic material. In one example, the hole 208 is configured tobecome a backside gas passage of an electrostatic chuck 112. In anotherexample, the hole 208 is configured to become a passage of withinanother type of ceramic substrate.

The ceramic porous plug 202 is fully sintered prior to being disposed inthe hole 208 of the ceramic body 204 at operation 702. Alternatively,the ceramic porous plug 202 may be partially sintered or fullyunsintered prior to being disposed in the hole 208 at operation 702.

Likewise, the ceramic body 204 may be partially sintered or fullyunsintered prior to receiving in the ceramic porous plug 202 into thehole 208 at operation 702. Alternatively, the ceramic porous plug 202may be fully sintered prior to receiving in the ceramic porous plug 202into the hole 208 at operation 702. In some examples, an unsinteredceramic porous plug 202 is disposed in the hole 208 of an unsintered,partially sintered, or fully sintered ceramic body 204 at operation 702.In some examples, a partially sintered ceramic porous plug 202 isdisposed in the hole 208 of an unsintered, partially sintered, or fullysintered ceramic body 204 at operation 702. In still other examples, afully sintered ceramic porous plug 202 is disposed in the hole 208 of anunsintered or partially sintered ceramic body 204 at operation 702.

At operation 702, the ceramic porous plug 202 may be disposed completelyin the hole 208 such that the bottom surface 306 of the ceramic porousplug 202 is flush with or is recessed from the bottom surface 238 of theceramic body 204. Alternatively, the ceramic porous plug 202 may bedisposed in the hole 208 such that the bottom surface 306 of the ceramicporous plug 202 is protrudes beyond from the bottom surface 238 of theceramic body 204. In some examples, the bottom surface 306 of theceramic porous plug 202 may protrude enough that the ceramic porous plug202 mates with a recess 602 formed in the bottom surface 238 of theceramic body 204.

One or both of the ceramic porous plug 202 and the ceramic body 204 maycomprise different types of ceramic material. For example, either one orboth of the ceramic porous plug 202 and the ceramic body 204 may befabricated with different size powder and or different types of ceramicmaterial as discussed above.

At operation 704 of the method 700, the ceramic material of the porousplug 202 and the ceramic structure are sintered together to form aceramic-to-ceramic bond therebetween. At operation 704, ceramic materialof the porous plug 202 and the ceramic structure are sintered togetherto form a solid contiguous body of fired ceramic.

Utilized to form an electrostatic chuck 112, operation 704 includessintering the ceramic material of the porous plug 202 and the ceramicbody 204 together to form a ceramic-to-ceramic bond therebetween. Atoperation 704, ceramic material of the porous plug 202 and the ceramicbody 204 are sintered together to form a solid contiguous body ofceramic.

Thus, an electrostatic chuck and method for forming the same have beendescribed above which leverage a ceramic-to-ceramic bond to eliminatethe need for adhesives to secure a porous plug in a ceramic body of theelectrostatic chuck. As the porous plug and body of the electrostaticchuck become a singular ceramic body, chuck failure modes are reducedwhile chuck service life is extended. Moreover, as there is no adhesivessecuring the plug to the chuck body, the amount of contamination ascompared to conventional designs is significantly reduced, whichadvantageously improves production yields. As such, ceramic-to-ceramicbonding of the ceramic porous plug to the ceramic body results in arobust and reliable electrostatic chuck with vastly improvedchuck-to-chuck performance uniformity. These benefits provide asignificant reduction in the cost of ownership, while synergisticallyimproving production yields and production capacity due to reducedparticle contamination and longer mean times between service intervalsassociated with the use of the electrostatic chuck.

While the foregoing is directed to embodiments of the disclosure, otherand further embodiments may be devised without departing from the basicscope thereof, and the scope thereof is determined by the claims thatfollow. As is apparent from the foregoing general description and thespecific embodiments, while forms of the present disclosure have beenillustrated and described, various modifications can be made withoutdeparting from the spirit and scope of the present disclosure.Accordingly, it is not intended that the present disclosure be limitedthereby.

We claim:
 1. An electrostatic chuck comprising: a ceramic body having asubstrate support surface and a bottom surface, an electrode and a gaspassage extending between the substrate support surface and the bottomsurface; and a ceramic porous plug secured in a portion of the gaspassage disposed between the electrode and the bottom surface by aceramic-to-ceramic bond.
 2. The electrostatic chuck of claim 1, whereinthe ceramic porous plug is sintered to the ceramic body.
 3. Theelectrostatic chuck of claim 1, wherein the ceramic porous plug as agrain size similar to a grain size of a portion of the ceramic bodycontacting the ceramic porous plug.
 4. The electrostatic chuck of claim1, wherein the ceramic porous plug as a grain size different than agrain size of a portion of the ceramic body contacting the ceramicporous plug.
 5. The electrostatic chuck of claim 1, wherein the ceramicporous plug as a grain size larger than a grain size of a portion of theceramic body contacting the ceramic porous plug.
 6. The electrostaticchuck of claim 1, wherein a bottom surface of the ceramic porous plug isflush with the bottom surface of the ceramic body.
 7. The electrostaticchuck of claim 1, wherein a bottom surface of the ceramic porous plug isrecessed from the bottom surface of the ceramic body.
 8. Theelectrostatic chuck of claim 1, wherein a bottom surface of the ceramicporous plug protrudes from the bottom surface of the ceramic body. 9.The electrostatic chuck of claim 8 further comprising: a temperaturecontrol base having an upper surface secured to the bottom surface ofthe ceramic body by an adhesive layer, temperature control base having agas delivery hole aligned with the gas passage formed in the ceramicbody, the bottom surface of the ceramic porous plug extending into thegas delivery hole such that the ceramic porous plug shields the adhesivelayer from the gas delivery hole and the gas passage.
 10. Theelectrostatic chuck of claim 1, wherein the ceramic porous plug furthercomprises: regions of different porosity.
 11. The electrostatic chuck ofclaim 1, wherein the ceramic porous plug is formed from a compositematerial.
 12. An electrostatic chuck comprising: a ceramic body having asubstrate support surface and a bottom surface, an electrode and a gaspassage extending between the substrate support surface and the bottomsurface; a ceramic porous plug disposed in a portion of the gas passagelocated between the electrode and the bottom surface, the ceramic porousplug sintered to the ceramic body; a temperature control base having agas delivery hole aligned with the gas passage formed in the ceramicbody and configured to flow backside gas to a support surface of theceramic body; and an adhesive layer securing the temperature controlbase to the bottom surface of the ceramic body.
 13. The electrostaticchuck of claim 12, wherein the ceramic porous plug as a grain sizelarger than a grain size of a portion of the ceramic body contacting theceramic porous plug.
 14. The electrostatic chuck of claim 12, wherein abottom surface of the ceramic porous plug is flush with the bottomsurface of the ceramic body.
 15. The electrostatic chuck of claim 12,wherein a bottom surface of the ceramic porous plug is recessed from thebottom surface of the ceramic body.
 16. The electrostatic chuck of claim12, wherein a bottom surface of the ceramic porous plug protrudes fromthe bottom surface of the ceramic body.
 17. The electrostatic chuck ofclaim 16, wherein the bottom surface of the ceramic porous plug extendsinto the gas delivery hole of the temperature control base such that theceramic porous plug shields the adhesive layer from the gas deliveryhole and the gas passage.
 18. The electrostatic chuck of claim 12,wherein the ceramic porous plug further comprises: regions of differentporosity.
 19. The electrostatic chuck of claim 12, wherein the ceramicbody has stacked regions of different grain sizes.
 20. A method forfabricating an electrostatic chuck, the method comprising: disposing aceramic porous plug at least partially in a hole formed in a sheet ofceramic material, the hole configured to become a fluid passage, theceramic porous plug disposed in a portion of the hole located between anelectrode and a bottom surface of the sheet of ceramic material; andsintering the ceramic material and ceramic porous plug to form aceramic-to-ceramic bond therebetween.